1. Field of the Invention
The present invention relates to a recovery device for an ink-jet recording apparatus for injecting ink to perform recording and an ink-jet recording apparatus having the recovery device.
2. Related Background Art
A conventional ink-jet recording apparatus supplies ink to a recording head, drives driving elements corresponding to a plurality of ink injection ports formed in an ink discharge surface of the recording head on the basis of a data signal, forms ink droplets to be injected from the ink injection ports to a recording medium, and deposits the ink droplets onto the recording medium, thereby recording information on the recording medium.
A conventional ink-jet recording apparatus of this type employs a recovery device. In general, in order to maintain a good ink injection state, an ink supply path is filled with ink even when the recording apparatus housing is opened, an ink tank is replenished or a recording head is replaced with a new one. The recovery device is activated to prevent an ink injection port from clogging caused by dust or increasing viscosity of the ink or deposition of ink around the discharge ports or air mixing in the ink supply path and hence to obtain a high quality image. According to the conventional recovery device, the ink injection ports are closed by a cap, the cap is connected to suction means such as a suction pump, and the suction means is activated to draw the ink in the recording head through the ink injection ports so that clogging is prevented to return to a desired discharge state.
In general, a sub-ink tank (subtank) is arranged adjacent to the recording head. After the ink is temporarily stored from a main ink tank (main tank) to the subtank, the ink is supplied to a recording head (e.g., a common chamber of the ink injection ports).
In the subtank, an ink level must be maintained within a predetermined range (e.g., a relatively high level) in order to stably supply the ink to the recording head. For this reason, the subtank must be evacuated by the suction means.
An openable ventilation means is connected to the cap. The ventilation means is closed during an operation with suction force effected by negative pressure and generated in the ink supply path, e.g., during an ink recovery operation as well as during transportation. During normal capping, the ventilation means is open to communicate with an atmospheric pressure, thereby preventing air from entering the nozzles.
In the conventional ink-jet recording apparatus, the air-absorbing tube from the subtank is directly connected to the suction means, and an abosrbing tube from the cap is also directly connected to the pump. When ink clogging is caused by deposition and an increase in viscosity of the ink at the ink injection ports (i.e., nozzles), the ink can be no longer drawn from the ink injection ports. Therefore, it is often very difficult or impossible to perform the recovery operation.
An orifice diameter of each ink injection port tends to be decreased as the number of dots is increased so as to obtain a clear image. Lack of recovery in such ink injection ports poses a crucial problem.